Far-field light field simulation test system for space laser communication terminal

Abstract

The invention discloses a far-field light field simulation test system for a laser communication terminal. The far-field light field simulation test system comprises a primary mirror assembly, a secondary mirror assembly, a turning mirror assembly, a rod assembly, a focal plane assembly and a frame, the focal plane assembly is composed of a reflector, a spectroscope, a transmitting optical fiber, a receiving optical fiber, a light beam quality analyzer and a coated dichroic mirror. The far-field simulation test system is an off-axis reflection type optical system developed based on the geometrical optics theory. The test system is a core component applied to ground demonstration and verification of space laser communication, serves as a collimator for optical system installation and calibration of a terminal on one hand, provides a complete machine test platform for the space laser communication terminal on the other hand, can serve as a transmitting end to provide a parallel light source and can also serve as a receiving end, and the space laser communication terminal is convenient to use. The detected laser communication terminal is detected, and optical parameters of light beam quality and transmission efficiency of the detected laser communication terminal are effectively evaluated.

Description

Technical Field

[0001] The invention belongs to the technical field of optoelectronic testing, and in particular relates to a far-field light field simulation test system for a laser communication terminal. Background Art

[0002] As a new generation of space communication technology, space laser communication technology has the characteristics of high transmission rate, long distance, strong anti-interference and strong confidentiality. It can meet the current growing demand for information transmission and is a hot topic of research in countries around the world. Space laser communication terminals are carried on satellite platforms and can realize satellite-to-ground communication, inter-satellite communication and networking communication. For satellite platforms, it is difficult to directly carry them on actual platforms during the research and development, experiment and application evaluation stages, and it is difficult to conduct in-orbit experiments. A large number of simulation studies must be carried out on the ground before actual onboard experiments can be carried out.

[0003] In summary, a far-field light field simulation test system for laser communication terminals can be used. The far-field light field simulation system for laser communication terminals is a key device for realizing ground demonstration and verification. It can simulate the changes of laser beams after long-distance space transmission, and provide ideal goals and benchmarks for the installation, research and development, and testing of laser communication terminals. It can provide guidance for the research and development and design of laser communication terminals, and conduct experiments and performance tests on the developed terminal equipment. The solution to be introduced below was produced under this background. It has many advantages and meets the huge needs of the industry market. Summary of the invention

[0004] The technical problem solved by the present invention is: to propose a far-field light field simulation test system for a laser communication terminal, which is applied to the ground demonstration and verification project of space laser communication. The far-field light field simulation test device has two functions: one is to be used as a parallel light tube for the optical system installation and calibration of the terminal, and the other is to provide a whole machine test platform for the space laser communication terminal. It can not only be used as a transmitting end to simulate the long-distance transmission light field to provide a parallel light source for the terminal under test; it can also be used as a receiving end to receive and detect the laser beam emitted by the laser communication terminal under test, and effectively evaluate its optical parameters of beam quality and transmission efficiency.

[0005] In order to solve the above technical problems, the present invention discloses a far-field light field simulation test system for a space laser communication terminal, which is characterized by comprising a primary mirror assembly, a secondary mirror assembly, a turning mirror assembly, a rod assembly, a focal plane assembly and a frame;

[0006] The primary mirror assembly, the secondary mirror assembly, the turning mirror assembly, and the focal plane assembly are mounted on the frame through an optical mirror seat or a tooling, and the rod assembly is mounted between the primary mirror assembly and the secondary mirror assembly;

[0007] The focal plane assembly is composed of a reflector, a beam splitter, a transmitting optical fiber, a receiving optical fiber, a beam quality analyzer, an optical breadboard and a coated dichroic mirror;

[0008] The reflecting mirror, the beam splitter, the beam quality analyzer and the coated color separation mirror are mounted on the optical breadboard through an optical mirror seat or a tooling.

[0009] Furthermore, the primary mirror assembly, secondary mirror assembly, turning mirror assembly, and focal plane assembly form an off-axis reflective structural optical path. The primary mirror assembly and the secondary mirror assembly have a certain angle and spatial offset. After the signal light incident on the system reaches the primary mirror assembly at the rightmost end, it is reflected by the primary mirror assembly, focused and obliquely incident on the secondary mirror assembly at the left end. The laser beam is reflected by the secondary mirror assembly to the turning mirror assembly, and the turning mirror assembly directs the light beam vertically into the focal plane assembly. The signal light reception and signal light emission share the same optical path.

[0010] Furthermore, the main optical element materials of the primary mirror assembly, the secondary mirror assembly, the turning mirror assembly and the focal plane assembly are microcrystalline glass that is less affected by temperature stress.

[0011] Furthermore, the optical mirror mount adopts a peripheral support structure, is positioned by the side of the mirror body and the ground, and uses 6061 aluminum alloy with a similar expansion coefficient to the mirror body material to reduce the stress on the mirror body. The mirror mount is equipped with a translation adjustment mechanism, and three groups of adjustment screws are evenly arranged on the mirror chamber flange to adjust the pitch of the mirror body.

[0012] Furthermore, the secondary mirror assembly is provided with a lifting and adjusting structure and a light shield is installed to eliminate stray light.

[0013] Furthermore, the rod assembly is made of carbon fiber material with a low linear expansion coefficient to compensate for the mirror spacing between the primary and secondary mirror assemblies when the temperature changes.

[0014] Furthermore, the focal plane assembly is installed on an optical breadboard. After the incident signal light enters the focal plane assembly, it passes through a beam splitter and enters a beam quality analyzer and a plane reflector respectively. The plane reflector reflects all light energy to the coated reflector. The coated reflector reflects or transmits the signal light according to different wavelengths and focuses on the transmitting optical fiber and the receiving optical fiber respectively.

[0015] Furthermore, the beam splitter adopts a 1:9 beam splitting, 10% of the energy beam is reflected at 45° and enters the beam quality analyzer, and 90% of the energy beam enters the plane reflector.

[0016] Furthermore, the coated reflector has one side as a reflective surface and the other side as an anti-reflection surface. When the reflector of the coated reflector is placed at an angle of 45° to the incident light beam, it can completely reflect the 1540nm wavelength laser and completely transmit the 1563nm wavelength laser.

[0017] Furthermore, the transmitting and receiving optical fibers are mounted on an adapter plate through an optical fiber flange, which is then mounted on an adjustment frame through the adapter plate, and the optical fiber flange is adapted to an FC / APC interface and an SMA interface. The present invention has the following advantages:

[0018] Compared with the traditional collimator, the present invention places a point light source at the focus, which can only emit parallel light. The far-field simulation test system can simultaneously play the role of laser receiving and laser emitting through the focal plane component. And two optical fiber interface components are used to connect the transmitting light path and the receiving light path respectively, so as to realize the simultaneous testing of both ends during the terminal test process. In addition, the existence of the focal plane component also provides the possibility for subsequent system upgrades and the addition of functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. It should be noted that for the sake of clarity and ease of description, the drawings are not necessarily drawn to scale.

[0020] Figure 1 This is a layout diagram of the equipment of the far-field light field simulation test system for the laser communication terminal of the present invention;

[0021] Figure 2 This is an optical principle diagram of the laser communication terminal far-field light field simulation test system of the present invention;

[0022] Figure 3 is a schematic diagram of a primary mirror assembly of the present invention;

[0023] Figure 4 is a schematic diagram of a secondary mirror assembly of the present invention;

[0024] Figure 5 It is a schematic diagram of a folding mirror assembly of the present invention;

[0025] Figure 6 is a schematic diagram of a focal plane assembly of the present invention;

[0026] Figure 7 It is a schematic diagram of the optical fiber interface assembly of the present invention;

[0027] Figure 8 It is a point diagram of each field of view of the system of the present invention;

[0028] Fig. 9 is the system RMS curve of the +Y field of view of the present invention;

[0029] Fig.10 It is the system RMS curve of the +X field of view of the present invention.

[0030] Markings in the figure: 1-primary mirror assembly, 2-secondary mirror assembly, 3-turning mirror assembly, 4-rod assembly, 5-focal plane assembly, 6-frame, 7-reflector, 8-coated dichroic mirror, 9-reflector, 10-beam quality analyzer, 11-transmitting optical fiber, 12-receiving optical fiber, 13-adapter plate, 14-optical fiber flange, 15-exit pupil / entrance pupil, 301-primary mirror, 401-secondary mirror, 501-turning mirror.

[0031] Specific implementation methods

[0032] The present invention will be further described below in conjunction with the accompanying drawings.

[0033] In this embodiment, the equipment layout of the laser communication terminal far-field light field simulation test system is as follows: Figure 1 As shown, it includes a primary mirror assembly 1, a secondary mirror assembly 2, a turning mirror assembly 3, a rod assembly 4, a focal plane assembly 5 and a frame 6;

[0034] The primary mirror assembly 1, the secondary mirror assembly 2, the deflection mirror assembly 3, and the focal plane assembly 5 are mounted on the frame through an optical mirror seat or a tooling, and the rod assembly 4 is installed between the primary mirror assembly 1 and the secondary mirror assembly 2;

[0035] The main components are made of microcrystalline glass, which is less affected by temperature stress and ensures the imaging quality of the system.

[0036] like Figure 2 As shown in the optical schematic diagram of the far-field light field simulation test system of the laser communication terminal, the signal light receiving and the signal light transmitting share the same optical path, and the optical path adopts an off-axis reflective structure. The primary mirror component 1 and the secondary mirror component 2 have a certain angle and spatial offset, and the light beam will not be blocked during the transmission process;

[0037] Take the receiving optical path as an example: a parallel light beam enters the system from the entrance pupil 15, reaches the primary mirror assembly 1 at the far right, is reflected by the primary mirror assembly 1, and is focused and obliquely incident on the secondary mirror assembly 2 at the left;

[0038] The laser beam is reflected by the secondary mirror assembly 2 to the folding mirror assembly 3, and the folding mirror assembly 3 makes the beam vertically incident on the focal plane assembly 5;

[0039] The focal plane assembly 5 includes a beam splitter 7, a dichroic mirror 8, a reflector 9, a mass analyzer 10 and two optical fibers 11 and 12, which together play the functions of receiving, emitting and detecting the laser beam;

[0040] According to the reversibility of the optical path, the emitted light is emitted from the end face of the optical fiber, passes through the dichroic mirror 8, the reflector 9, the beam splitter 7, the folding mirror 501, the secondary mirror 401 and the primary mirror 301, and is collimated into a 300 mm diameter parallel beam, which is emitted from the system exit pupil 15.

[0041] like Figure 3 As shown in the schematic diagram of the primary mirror assembly 1, preferably, the primary mirror 301 has a size of 320 mm*45 mm, which is a small reflector, and a peripheral support structure is adopted here;

[0042] The positioning reference selects the side and bottom surfaces of the mirror body, and places the primary mirror 301 in a relatively closed mirror chamber;

[0043] Preferably, the material of the support structure is aluminum alloy 6061, which has a linear expansion coefficient relatively close to that of the primary mirror 301 material;

[0044] In order to reduce the stress on the primary mirror 301, an elastic support structure is used in the axial direction of the primary mirror 301, and two pieces of polytetrafluoroethylene are bonded radially to buffer the stress generated when the primary mirror 301 contacts the mirror chamber, so that the primary mirror 301 obtains a better mirror surface shape, thereby enabling the system to obtain better image quality;

[0045] Four groups of adjustment screws are evenly arranged on the flange of the mirror chamber to meet the pitch adjustment of the main mirror 301. Two waist grooves are opened on the mirror seat, and the two waist grooves are on the same circumference to facilitate the rotation adjustment of the main mirror 301. The mirror seat is provided with a translation adjustment mechanism to meet the two-dimensional translation adjustment of the main mirror assembly 1.

[0046] like Figure 4 As shown in the structural diagram of the secondary mirror assembly 2, a peripheral support structure is adopted, and the side and bottom surfaces of the mirror body are selected as the positioning reference, and the secondary mirror 401 is placed in a relatively closed mirror chamber;

[0047] Preferably, the material of the support structure is aluminum alloy 6061, which has a linear expansion coefficient relatively close to that of the secondary mirror 401 material;

[0048] In order to reduce the stress on the secondary mirror 401, polytetrafluoroethylene is bonded in the axial and radial directions of the secondary mirror 401 to buffer the stress generated when the secondary mirror 401 contacts the mirror chamber, so that the secondary mirror obtains a better mirror surface shape, thereby enabling the system to obtain better image quality;

[0049] Three sets of adjustment screws are evenly arranged on the flange of the mirror chamber to meet the pitch adjustment of the secondary mirror 401. Two waist grooves are opened on the mirror seat, and the two waist grooves are on the same circumference to facilitate the rotation adjustment of the secondary mirror 401. The mirror seat is provided with a translation adjustment mechanism to meet the two-dimensional translation adjustment of the secondary mirror.

[0050] Preferably, the secondary mirror 401 is provided with a one-dimensional lifting adjustment structure and a light shield, and the secondary mirror assembly 2 is mounted on two sets of translation guide rails;

[0051] A rod assembly is installed between the primary mirror assembly 1 and the secondary mirror assembly 2. Preferably, the linear expansion coefficient of the carbon fiber is low, which meets the requirement of compensating the mirror distance between the primary and secondary mirrors when the temperature changes.

[0052] like Figure 5 As shown in the schematic diagram of the folding mirror assembly 3, a peripheral support structure is adopted, and the positioning reference selects the side and bottom surfaces of the mirror body, and the folding mirror 501 is placed in a relatively closed mirror chamber;

[0053] Preferably, the material of the support structure is aluminum alloy 6061, which has a linear expansion coefficient relatively close to that of the material of the folding mirror 501;

[0054] In order to reduce the stress on the folding mirror 501, polytetrafluoroethylene is bonded in the axial and radial directions of the folding mirror 501 to buffer the stress generated when the folding mirror 501 contacts the mirror chamber, so that the folding mirror 501 obtains a better mirror surface shape and a better image quality;

[0055] Three groups of adjustment screws are evenly arranged on the flange of the mirror chamber to meet the pitch adjustment of the folding mirror 501. Two waist grooves are opened on the mirror seat, and the two waist grooves are on the same circumference to facilitate the rotation adjustment of the folding mirror 501. The mirror seat is provided with a translation adjustment mechanism to meet the two-dimensional translation adjustment of the folding mirror 501.

[0056] like Figure 6 As shown in the schematic diagram of the focal plane assembly 5, each component or device is installed on the optical breadboard through an optical lens holder or a tooling, and has a certain adjustment space. Preferably, the incident system light beam is reflected by the folding mirror assembly 3 at 45° and enters the focal plane assembly 5, and first hits the beam splitter 7. The beam splitter 7 adopts a 1:9 splitting, and 10% of the energy beam is reflected at 45° and enters the beam quality analyzer 10, and the remaining 90% of the energy beam enters the second optical element-the plane reflector 9;

[0057] The plane reflector 9 reflects all the light energy at 45° to the reflective surface of the coated dichroic mirror 8;

[0058] The coated dichroic mirror 8 has one side as a reflective surface and the other side as an anti-reflective surface. When the coated dichroic mirror is placed at 45° to the incident light beam, it can completely reflect the 1540nm wavelength laser and completely transmit the 1563nm wavelength laser, and a fiber optic interface assembly is placed at the focal position of the two light beams.

[0059] like Figure 7 As shown in the schematic diagram of the optical fiber interface assembly, the optical fiber flange 14 on the optical fiber interface assembly is installed on the adapter plate 13, and is installed on the adjustment frame through the adapter plate to achieve adjustment of the optical fiber. The optical fiber flange 14 is adapted to the FC / APC interface and the SMA interface.

[0060] like Figure 8As shown in the system's field of view point diagram, the preferred scattered diameter is <4.7m. According to the formula

[0061] ftanθ2=d2

[0062] The system focal length f = 6500mm, and the theoretical design value θ = 0.144″ can be calculated, which meets the beam parallelism field requirement.

[0063] like Fig. 9 , Fig.10 As shown in the schematic diagram of the system RMS curve of the +X and +Y fields of view, preferably, at the detection wavelength λ=0.6328um, the full field of view of the collimator is ±0.0442°, the image size is 10mm, and the RMS of the system full field of view design value is ≤0.018λ. Considering the processing and adjustment errors, the system RMS ≤λ / 15 (λ=0.6328um) can be achieved, which can meet the high-resolution testing work.

[0064] Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solution of the present invention by using the above disclosed methods and technical contents without departing from the spirit and scope of the present invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention. The contents not described in detail in the specification of the present invention belong to the known technology of professional and technical personnel in this field.

Claims

1. A laser communication terminal far-field light field simulation test system, characterized in that: It includes a primary mirror assembly, a secondary mirror assembly, a turning mirror assembly, a rod assembly, a focal plane assembly and a frame; The primary mirror assembly, the secondary mirror assembly, the turning mirror assembly, and the focal plane assembly are mounted on the frame through an optical mirror seat or a tooling, and the rod assembly is mounted between the primary mirror assembly and the secondary mirror assembly; The focal plane assembly is composed of a reflector, a beam splitter, a transmitting optical fiber, a receiving optical fiber, a beam quality analyzer, an optical breadboard and a coated dichroic mirror; The reflecting mirror, the beam splitter, the beam quality analyzer and the coated color separation mirror are mounted on the optical breadboard through an optical mirror seat or a tooling.

2. A laser communication terminal far-field light field simulation test system as described in claim 1, characterized in that: The primary mirror assembly, secondary mirror assembly, folding mirror assembly, and focal plane assembly form an off-axis reflective structural optical path. The primary mirror assembly and the secondary mirror assembly have a certain angle and spatial offset. After the signal light entering the system reaches the primary mirror assembly at the rightmost end, it is reflected by the primary mirror assembly and focused and obliquely incident to the secondary mirror assembly at the left end. The laser beam is reflected by the secondary mirror assembly to the folding mirror assembly, and the folding mirror assembly directs the light beam to be vertically incident on the focal plane assembly. The signal light reception and signal light emission share the same optical path.

3. A laser communication terminal far-field light field simulation test system as described in claim 1, characterized in that: The main optical element materials of the primary mirror assembly, the secondary mirror assembly, the turning mirror assembly and the focal plane assembly are microcrystalline glass that is less affected by temperature stress.

4. A laser communication terminal far-field light field simulation test system as described in claim 1, characterized in that: The optical mirror mount adopts a peripheral support structure and is positioned by the side of the mirror body and the ground. 6061 aluminum alloy with a similar expansion coefficient to the mirror body material is used to reduce the stress on the mirror body. The mirror mount is equipped with a translation adjustment mechanism, and three groups of adjustment screws are evenly arranged on the mirror chamber flange to adjust the pitch of the mirror body.

5. A laser communication terminal far-field light field simulation test system as described in claim 1, characterized in that: The secondary mirror assembly is provided with a primary lifting adjustment structure and a light shield is installed to eliminate stray light.

6. A laser communication terminal far-field light field simulation test system as described in claim 1, characterized in that: The rod assembly is made of carbon fiber material with a low linear expansion coefficient to compensate for the mirror spacing between the primary and secondary mirror assemblies when the temperature changes.

7. A laser communication terminal far-field light field simulation test system as described in claim 1, characterized in that: The focal plane assembly is mounted on an optical breadboard. After the incident signal light enters the focal plane assembly, it passes through a beam splitter and enters a beam quality analyzer and a plane reflector respectively. The plane reflector reflects all light energy to the coated reflector. The coated reflector reflects or transmits the signal light according to different wavelengths and focuses on the transmitting optical fiber and the receiving optical fiber respectively.

8. A laser communication terminal far-field light field simulation test system as described in claim 7, characterized in that: The beam splitter adopts 1:9 beam splitting, 10% of the energy beam is reflected at 45° and enters the beam quality analyzer, and 90% of the energy beam enters the plane reflector.

9. A laser communication terminal far-field light field simulation test system as described in claim 7, characterized in that: The coated reflector has one side as a reflective surface and the other side as an anti-reflection surface. When the reflector of the coated reflector is placed at an angle of 45° to the incident light beam, the 1540nm wavelength laser can be completely reflected and the 1563nm wavelength laser can be completely transmitted.

10. A laser communication terminal far-field light field simulation test system as described in claim 1, characterized in that: The transmitting and receiving optical fibers are installed on the adapter plate through the optical fiber flange, and are installed on the adjustment frame through the adapter plate. The optical fiber flange is adapted to the FC / APC interface and the SMA interface.

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